{"id":"EUVD-2026-107388","revision":"6be97f72d4c54d759091ab0a9e87fd60","records":[{"revision":"6be97f72d4c54d759091ab0a9e87fd60","observedAt":"2026-10-28T00:54:41.676+00:00","statement":{"source":"euvd","id":"EUVD-2026-107388","aliases":["CVE-2026-113799","GHSA-26w4-8w32-4x3v"],"title":"Slack Morphism is a client library for Slack Web/Events API/Socket Mode and Block Kit. Versions 1.0.0 through 2.27.0 expose the correct Slack request HMAC when signature verification fails. For an invalid request, `slack-morphism` computes …","description":"Slack Morphism is a client library for Slack Web/Events API/Socket Mode and Block Kit. Versions 1.0.0 through 2.27.0 expose the correct Slack request HMAC when signature verification fails. For an invalid request, `slack-morphism` computes the correct signature for the attacker-controlled timestamp and request body and stores it in `SlackEventWrongSignatureError.generated_hash`. The error's `Debug` and `Display` representations expose that value, and the default Axum listener error handler logs it at error level. An attacker who can both reach the application's Slack callback endpoint and read its application/service logs can therefore use the verifier as a chosen-message HMAC oracle. The attacker can send an arbitrary request with an invalid signature, recover the correct signature from the resulting log entry, and resend the same request within the five-minute freshness window. The second request passes Slack Morphism's signature verification and reaches the protected application callback without the attacker knowing the Slack signing secret. Version 2.28.0 patches the issue.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N","score":5.3,"severity":null}],"references":["https://github.com/abdolence/slack-morphism-rust/security/advisories/GHSA-26w4-8w32-4x3v","https://github.com/abdolence/slack-morphism-rust/pull/387","https://github.com/abdolence/slack-morphism-rust/commit/ac95d0d4539d0eac548a8db99c51c0c1ae832756","https://github.com/abdolence/slack-morphism-rust/releases/tag/v2.28.0"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-107388","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Oct 21, 2026, 4:15:10 PM","dateUpdated":"Oct 21, 2026, 4:15:10 PM"},"relatedAdvisories":[],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-107388","identifiers":["EUVD-2026-107388","CVE-2026-113799","GHSA-26w4-8w32-4x3v"]},"retained":false,"historicalAffected":[]}],"coverage":[]}